The present invention relates to the field of assemblies for fastening ground engaging tools to support structures on powered ground engaging equipment.
Many types of excavating equipment utilize replaceable ground engaging tools such as digging teeth. These teeth erode through use and are replaced as needed. For example, depending on the conditions, a given adapter could be re-equipped with from 5 to 30 teeth to maintain a sharp penetrating edge during excavation. The ease of replacement of the teeth is important because it minimizes the amount of wasted throwaway material and also minimizes the downtime of the digging equipment.
The prior art assemblies used to attach a tooth to the adapter consist mainly of two designs, the wedge design and the pin design. In the wedge design, the tooth is joined to the adapter by wedges that are hammered into corresponding slots in the tooth and the adapter. This design has the disadvantage that the wedges would often become dislodged during use of the excavating equipment. To prevent this problem, the wedge was tack-welded in place. However, removal of the wedges was then difficult and time consuming. Removal of teeth on a dragline bucket, for example, required that the bucket be turned on its front end to gain access to the wedges. Furthermore, during removal, the wedges had a tendency to shatter or break causing pieces to jam in the slots and pose a serious safety hazard to workers. Wedge designs are shown, for example, in U.S. Pat. No. 3,256,622.
Pin assemblies are shown in U.S. Pat. No. 2,121,993. This patent discloses a threaded pin and insert assembly for securing a tooth onto the adapter. The threaded insert is placed into the adapter pin opening. The tooth is placed over the adapter. A lock washer is concentrically placed over the pin opening on the tooth. The pin is then screwed into the insert. This assembly has the disadvantage of being cumbersome and complex in design making it difficult to use and increasing the time needed to replace the tooth. As well, the pin has a tendency to loosen from the insert while the tooth is in use. Another pin assembly is shown in U.S. Pat. No. 3,410,010 which discloses a dipper tooth having a detent and key assembly inserted into a passage in the tooth and adapter. This assembly suffers from the drawback that the key would often fall out of the passage during use of the tooth allowing the tooth to fall off the adapter.
Still another locking assembly is shown in U.S. Pat. No. 6,018,896. This patent discloses a locking device for a ground-engaging-tool. The device has a wedge-shaped pin that is held in place by a pin retainer inserted into a cavity in the tool support structure. The wedge-shaped pin holds the tool in position on the support structure by directly engaging the tool and support structure to transmit large tool-removing forces into the support structure. The pin retainer holds the pin in position by engaging the support structure and pin to resist the relatively small pin-removing forces. The pin retainer itself does not transmit or resist large tool-removing forces. That is the job of the pin. Although this coupling device performs well in dry friable material, it is difficult to remove if fluidized material penetrates the coupling device and cements the pin in place.
Thus there is a need for an assembly to lock a removable ground engaging tool to a support structure in such a way that the locking assembly is easy to use, reliable, and economical to manufacture. With the increased awareness of worker safety issues, it is particularly important that such assemblies be easy to install and do not pose a danger to workers.
The present invention provides for an assembly for locking a first workpiece to a second work piece wherein the first workpiece is mountable to the second workpiece. The assembly comprises a locking assembly and magnetic means for holding the assembly together in locking configuration.
In one embodiment of the present invention, there is provided an assembly for locking a first workpiece mountable onto a second workpiece. The first workpiece has an opening adapted to allow a locking pin to pass therethrough. The opening is cooperatively disposed with respect to a pin receiving means in said second workpiece when the first workpiece is mounted on the second workpiece. At least one of the first and second workpieces has a recess to receive a pin carrier. The assembly comprises a locking pin adapted to pass through the opening and be received by the pin receiving means when the first workpiece is mounted on said second workpiece. The assembly also comprises a pin carrier receivable in the recess. The pin carrier has a pin receiving orifice and is alignable with both the opening and the pin receiving means when the first workpiece is mounted on the second workpiece. The assembly also comprises magnetic means on the locking pin and/or the pin carrier to magnetically attract the locking pin and the pin carrier.
In a further embodiment of the present invention, there is provided an assembly for locking a first workpiece to a second workpiece wherein the first workpiece has a slot in the lower surface of one end opposite to a point and a first opening in its upper surface extending into the slot and the second workpiece has a boss on its upper surface corresponding to the slot in the first workpiece. When the first workpiece is slid onto the second workpiece, the slot engages the boss. The assembly comprises a pin carrier which is slidably receivable into the slot in the first workpiece. It has a pin receiving opening on its upper surface aligning with the first opening in the first workpiece when the pin carrier is inserted into the slot. The assembly also comprises a pin for insertion into the pin receiving opening in the first workpiece and the pin carrier for locking the tooth to the adaptor. The assembly may further comprise magnetic means to magnetically attract the pin, pin carrier, first workpiece, and/or the second workpiece.
In a further embodiment of the present invention, there is provided a method of assembling a first workpiece to a second workpiece comprising the step of mounting a first workpiece on a second workpiece. The first workpiece has an opening being cooperatively disposed with respect to a pin receiving means in the second workpiece when the first workpiece is mounted on the second workpiece. At least one of the first and second workpieces has a recess to receive a pin carrier. The method further comprises the step of inserting a pin carrier into the recess. The pin carrier has a pin receiving orifice which is alignable with both the opening and the pin receiving means when the first workpiece is mounted on the second workpiece. The method further comprises inserting a pin through the opening to be received by the pin receiving means when the first workpiece is mounted on the second workpiece. The method may further comprise the step of magnetically attracting the pin and the pin carrier to maintain the first workpiece on the second workpiece.